Fix range "arithmetic"

Subtracting anything from an empty range should return an empty range, not an assert() failure

diff --git a/libs/evoral/evoral/Range.hpp b/libs/evoral/evoral/Range.hpp
index 476970f663a860e232014a60b9aaa145adafbe84..230b28974722f4c45b3c0786ce87e84a6b0f9fc1 100644 (file)
--- a/libs/evoral/evoral/Range.hpp
+++ b/libs/evoral/evoral/Range.hpp
@@ -137,6 +137,7 @@ struct /*LIBEVORAL_API*/ Range {
        Range (T f, T t) : from (f), to (t) {}
        T from; ///< start of the range
        T to;   ///< end of the range (inclusive: to lies inside the range)
+       bool empty() const { return from == to; }
 };
 
 template<typename T>   
@@ -215,7 +216,7 @@ RangeList<T> subtract (Range<T> range, RangeList<T> sub)
        RangeList<T> result;
        result.add (range);
 
-       if (sub.empty ()) {
+       if (sub.empty () || range.empty()) {
                return result;
        }